1. Field of the Invention
The present invention relates to a reflector for collecting and redirecting light from a light source. Specifically, the invention relates to a reflector usable with, for example, a standard light emitting diode (LED) package utilizing an epoxy housing with a top facing lens.
2. Description of the Related Art
The ability to maximize light output from a light source increases energy efficiency and reduces manufacturing cost. By minimizing light losses, i.e. light rays not directed into the desired light pattern, all the light generated by a signal may be used. Maximizing a signals light output in the desired light pattern minimizes the number of and power level required for light emitting devices that would otherwise be needed to overcome light losses previously accepted as a design loss.
As shown in FIG. 1, standard light emitting diodes utilize an epoxy housing wherein a LED die 1 is located. When current is applied, the die activates and emits light. The light is reflected upward by one of the leads 15 which is in the form of a cup 20. The majority of the light is directed out of the top of the housing 10 through a lens 5 which directs it in a conical distribution pattern with an angle, in a standard LED, of approximately 20 to 30 degrees. FIG. 2 shows a typical light distribution emitted by a light emitting diode. The majority of light is projected forward in the desired direction but a large percentage (40-50%) is directed in other directions and is therefore treated as a design loss in most applications.
The light distribution shown in FIG. 2, may be categorized into three components. As shown in FIG. 3, the main component of the LED light is directed vertically through the lens 5. However, a second component is not directed into the lens 5 but instead escapes out of the side of the housing 10 at an increased spreading angle to the vertical axis of the housing 10 as shown in FIG. 4. A third component of the light is subject to total internal reflection within the housing from which it exits at an increased angle as shown in FIG. 5.
Previous reflectors used with LEDs attempted to collect and redirect sideways emitted light but did not account for the light subject to total internal reflection, effectively wasting this component of the LED light output. It is an object of the present invention to provide an energy efficiency maximizing LED reflector which, in addition to redirecting sideways emitted LED light, also redirects the light rays subject to total internal reflection, thereby maximizing light output for an individual or cluster of LEDs.
The present invention provides a reflector for individual or groups of light emitting devices, for example LEDs. Redirecting light normally escaping through the side of an LED package, the reflector also redirects light that reflects under total internal reflection conditions within the LED housing. A second reflection surface of the reflector is aligned with the increased exit angle of the total internal reflection light component. Because the angle is higher than that of light escaping sideways from the LED housing, the second reflector surface appears as a step back in the first reflection surface and does not degrade the first surface""s ability to redirect the sideways escaping light component. Pairing light emitting devices in a shared reflector configuration with a light deflecting pattern on non-reflector surface areas of the reflector creates an oval light pattern with reduced sun phantom properties useful for creating traffic signals according to Institute of Traffic Engineers (ITE) specifications.